International Business Machines Corporation

Masashi Murai

Hiroaki Suzuki

Hideo Asano

Nobuya Matsubara

Kevin Roy Vannorsdel

Michio Nakajima

Masaomi Ikeda

Yumi Nagano

Steven Kelly Provazek

A method for controlling write current to a write head during data write on a hard disk drive is disclosed. A direct access storage device includes a rotating storage medium in which data are magnetically written, a write head for writing data in the rotating storage medium, and a write current control circuit for changing write current-value settings to be supplied to the write head according to a predetermined elapsed time from the beginning of a write operation.

Method for controlling write current to a write head during data write on a hard disk

A method and system are disclosed for controlling the application of a reset voltage pulse to a GMR sensor in a direct-access storage device (DASD), such that existing data is not damaged or altered. Each sensor is positioned or parked at a location reserved for reset pulse application, where no valid data is stored. A complex interrelated set of commands is then initiated, and upon completion of the entire set of interrelated commands, a reset pulse is applied to the GMR sensor. Any variation or interruption in the complex interrelated set of commands will result in a disarming of the reset pulse circuitry, effectively preventing an accidental or inadvertent application of the GMR reset pulse. Alternately, a group of GMR sensors each may be tracked to a reserve track, forming a reserve cylinder. Servo marks on the reserve track are sensed by a selected sensor and utilized to ensure no valid data is present. An alternate sensor is then temporarily selected, and a reset pulse is applied, timed to avoid occurrence over a servo mark.

Method and system for GMR sensor reset pulse application

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Kanagawa-ken, Japan

Masashi Murai